package com.ctrip.framework.apollo.configservice.util;

import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

import org.springframework.stereotype.Component;

import com.ctrip.framework.apollo.common.entity.AppNamespace;
import com.ctrip.framework.apollo.configservice.service.AppNamespaceServiceWithCache;
import com.ctrip.framework.apollo.core.ConfigConsts;
import com.google.common.base.Joiner;
import com.google.common.base.Strings;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;

/**
 * @author Jason Song(song_s@ctrip.com)
 */
@Component
public class WatchKeysUtil {
	private static final Joiner STRING_JOINER = Joiner.on(ConfigConsts.CLUSTER_NAMESPACE_SEPARATOR);
	private final AppNamespaceServiceWithCache appNamespaceService;

	public WatchKeysUtil(final AppNamespaceServiceWithCache appNamespaceService) {
		this.appNamespaceService = appNamespaceService;
	}

	/**
	 * Assemble watch keys for the given appId, cluster, namespace, dataCenter
	 * combination
	 */
	public Set<String> assembleAllWatchKeys(String appId, String clusterName, String namespace, String dataCenter) {
		Multimap<String, String> watchedKeysMap = assembleAllWatchKeys(appId, clusterName, Sets.newHashSet(namespace), dataCenter);
		return Sets.newHashSet(watchedKeysMap.get(namespace));
	}

	/**
	 * Assemble watch keys for the given appId, cluster, namespaces, dataCenter
	 * combination
	 *
	 * @return a multimap with namespace as the key and watch keys as the value
	 */
	public Multimap<String, String> assembleAllWatchKeys(String appId, String clusterName, Set<String> namespaces, String dataCenter) {
		Multimap<String, String> watchedKeysMap = assembleWatchKeys(appId, clusterName, namespaces, dataCenter);

		// Every app has an 'application' namespace
		if (!(namespaces.size() == 1 && namespaces.contains(ConfigConsts.NAMESPACE_APPLICATION))) {
			Set<String> namespacesBelongToAppId = namespacesBelongToAppId(appId, namespaces);
			Set<String> publicNamespaces = Sets.difference(namespaces, namespacesBelongToAppId);

			// Listen on more namespaces if it's a public namespace
			if (!publicNamespaces.isEmpty()) {
				watchedKeysMap.putAll(findPublicConfigWatchKeys(appId, clusterName, publicNamespaces, dataCenter));
			}
		}

		return watchedKeysMap;
	}

	private Multimap<String, String> findPublicConfigWatchKeys(String applicationId, String clusterName, Set<String> namespaces, String dataCenter) {
		Multimap<String, String> watchedKeysMap = HashMultimap.create();
		List<AppNamespace> appNamespaces = appNamespaceService.findPublicNamespacesByNames(namespaces);

		for (AppNamespace appNamespace : appNamespaces) {
			// check whether the namespace's appId equals to current one
			if (Objects.equals(applicationId, appNamespace.getAppId())) {
				continue;
			}

			String publicConfigAppId = appNamespace.getAppId();

			watchedKeysMap.putAll(appNamespace.getName(), assembleWatchKeys(publicConfigAppId, clusterName, appNamespace.getName(), dataCenter));
		}

		return watchedKeysMap;
	}

	private String assembleKey(String appId, String cluster, String namespace) {
		return STRING_JOINER.join(appId, cluster, namespace);
	}

	private Set<String> assembleWatchKeys(String appId, String clusterName, String namespace, String dataCenter) {
		if (ConfigConsts.NO_APPID_PLACEHOLDER.equalsIgnoreCase(appId)) {
			return Collections.emptySet();
		}
		Set<String> watchedKeys = Sets.newHashSet();

		// watch specified cluster config change
		if (!Objects.equals(ConfigConsts.CLUSTER_NAME_DEFAULT, clusterName)) {
			watchedKeys.add(assembleKey(appId, clusterName, namespace));
		}

		// watch data center config change
		if (!Strings.isNullOrEmpty(dataCenter) && !Objects.equals(dataCenter, clusterName)) {
			watchedKeys.add(assembleKey(appId, dataCenter, namespace));
		}

		// watch default cluster config change
		watchedKeys.add(assembleKey(appId, ConfigConsts.CLUSTER_NAME_DEFAULT, namespace));

		return watchedKeys;
	}

	private Multimap<String, String> assembleWatchKeys(String appId, String clusterName, Set<String> namespaces, String dataCenter) {
		Multimap<String, String> watchedKeysMap = HashMultimap.create();

		for (String namespace : namespaces) {
			watchedKeysMap.putAll(namespace, assembleWatchKeys(appId, clusterName, namespace, dataCenter));
		}

		return watchedKeysMap;
	}

	private Set<String> namespacesBelongToAppId(String appId, Set<String> namespaces) {
		if (ConfigConsts.NO_APPID_PLACEHOLDER.equalsIgnoreCase(appId)) {
			return Collections.emptySet();
		}
		List<AppNamespace> appNamespaces = appNamespaceService.findByAppIdAndNamespaces(appId, namespaces);

		if (appNamespaces == null || appNamespaces.isEmpty()) {
			return Collections.emptySet();
		}

		return appNamespaces.stream().map(AppNamespace::getName).collect(Collectors.toSet());
	}
}
